AI's are VERY effective in PCT
Nolva being promoted as post cycle therapy (pct) is one of the greatest travesties of the modern gear era. Clomifen is both superior and actually clinically established for treatment of male andropause from steroid use.
the reason that letro is not reccomended for post cycle therapy (pct) is that it suppresses estrogen TOO low and because of the rebound issue (letrozole and arimidex both upregulate aromatase production).
also agree that for many years people used no AI's or SERMS, and a good percentage of those people did not get gyno. Though over time with age and use, the percentage that dont get gyno is less and less. Use of an Aromatase inhibitor (AI) during early cycles is still essential, even just low dose for those that are not prone to gyno, because eventually most of them will.
the prone people are those that had different exposure to E and other hormones prior to use... ie people with E issues during puberty, higher than average aromatase levels, over production of GH or prolactin, high thryoid, exposure to xenoestrogen, progestenic issues, low DHT levels, etc... However over time (with age) and exposure to various AAS, most people end up in the same boat. this can be "resisted" by using the right preventative measures (including not getting fat, since fat is a good soruce of aromatase)
do agree that AI's should be used to control, not eliminate estrogen. But you really only need a small amount of E, any more just causes sides and suppresses the HPGA.